We have so far looked at seven different control cards, BEGIN, END,
SOLVE, and EXIT are all TYPE 0 control cards. ROWS, MATRIX, and RHS are
all TYPE N control cards. We will discuss examples of TYPE 1 control
cards below.
 The "END" statement is used to terminate the data following a TYPE N
control card. In fact, any card with a punch in columns one through six
will end such a TYPE N control, however, the END statement makes the
program clear. For the above reason, it is imperative that data cards do
not have any punching in columns 1 to 6 or an error will occur.
 The following is a listing of each control card and its function.


7.1 TYPE 0 Control Cards


7.1.1 BEGIN--This is always the first card for any problem. (More than
 one problem may be solved in a single run). BEGIN causes the
 storage areas for the problem to be zeroed out and sets the tol-
 erance and frequency parameters to their default values. It is
 somewhat analogous to "INITIALZ" in MPSX.


7.1.2 END--This statement should be used to terminate the data that
 follows a TYPE N control card.


7.1.3 EOF--This statement instructs LCRAND to read the next card from
 FORTRAN input unit 5. This unit number is the default for the
 program and thus if it was placed in a card input stream, it
 would typically cause no change. It is used in conjunction with
 the control card "TAPE". "TAPE" causes the program to read from
 FORTRAN unit 11 which could be a disk or tape file. Thus the
 problem data (ROWS, MATRIX, RHS) could be stored on a secondary
 storage device and read in from there. In this case, EOF would
 be placed at the end of this data set defined as FORTRAN unit 11
 to instruct the program to return to reading control statements
 from the card input stream (see section 8).